1. Field of the Invention
The present invention relates to a partially-fluorinated-alkyl compound, a lubricant for recording medium including the partially-fluorinated-alkyl compound, and a recording medium having formed a lubricant layer comprising the lubricant.
2. Description of Related Art
As conventional recording media, for example, magnetic recording media, there have been known so-called metal thin film type magnetic recording media including a magnetic layer which is formed by depositing a ferromagnetic metal material on a nonmagnetic support by using, for example, a vapor deposition process, and so-called coating type magnetic recording media including a magnetic layer which is formed by applying to a nonmagnetic support a magnetic coating composition including very fine magnetic particles and a resin binder. In these conventional magnetic recording media, the magnetic layer has extremely excellent surface smoothness and hence, the substantial contact area of the magnetic layer with a sliding member, such as a magnetic head or a guide roller, is large, namely, the coefficient of friction is large, leading to problems in that a so-called sticking phenomenon due to cohesion is likely to occur and the transport properties and durability of the magnetic recording media are poor.
For solving the problems, various lubricants are studied and, conventionally, it has been attempted to incorporate or apply, as a topcoat, a higher fatty acid or an ester thereof to the magnetic layer in the magnetic recording medium to lower the coefficient of friction.
The magnetic recording medium is used under severe conditions, and therefore the lubricant used in the magnetic recording medium is required to have extremely excellent properties. However, the lubricants conventionally used are currently difficult to meet the requirements.
Specifically, the lubricant used in the magnetic recording medium must meet such requirements: (1) for securing a predetermined lubricating effect when used in cold places, that the lubricant have excellent properties at low temperatures; (2) for removing a problem of the spacing between a magnetic head and the recording medium, that the lubricant applied to the recording medium have an extremely small thickness and exhibit satisfactory lubricating properties; and (3) that the lubricant endure long-time or long-term use and maintain the lubricating effect.
As a lubricant for metal thin film type magnetic recording medium, Japanese Patent Application Laid-Open Specification No. 6-41561 discloses a fluorine-containing alkyl diester of succinic acid represented by the following formula (i):R1—CH(COOR2)CH2COOR3  (i)
wherein R1 represents an aliphatic alkyl group or an aliphatic alkenyl group; and one of R2 and R3 represents a fluoroalkyl ether group, and another represents a fluoroalkyl group, a fluoroalkenyl group, a fluorophenyl group, an aliphatic alkyl group, or an aliphatic alkenyl group.